Control system for winch drives



Jan. 21, 1947. K. MAHNKE 2,414,473]

CONTROL SYSTEM FOR WINCH DRIVES Filed Nov. 20, 1945 V s Shets-Sheet 1 z/w- Fig.1. I64 E I68 ma 19.9,

Manual W lu/oma/n':

' WITNESSES: 7 INVENTOR (i4 Kurf/Maf/nre'.

cup-W .fMfiW ATTORNEY Jan. 21, 1947. K, MAHNKE 2,414,473

'CONTRQL SYSTEM FOR WINCH DRIVES Filed Nov. 20., 1943 s Sheets-Sheet a 64/36 Z/ lawyer" WITNESSES: INVENTOR ATTORNEY Patented Jan. 21, 1947 UNITED STATES. PATENT O F F 1 CE 23143473 CONTROL sfYs'rEM FOR WINCH DRIVES Kurt Mahnke, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation. of; Pennsylvania Application November 20, 1943, Serial No. 511,038

My invention relates to control systems for rotation of the hawserdru-mdriven by the motor.

11' Claims. (Cl. 254 172) son the operation of the winch drive is practically This control arrangement is so designed that the torque of the winch motor is progressively increased when the drum, under excessive cable pull, is forced to pay-out, and is progressively decreased when the motor torque exceeds the cable pull and causes the drum to heave in. As a result; the paid-out length of cable is automatically kept; within desired limits. It is also known in such systems to control the field excitation ofthe generator by-means of a tensionresponsivedevice with the effect of: reducing the torque of the winch motor when the tension or pull, of the towing cable becomes too-high.

It is an objectv of myinvention to improve variable voltage drives of the above-mentioned type so asto afford amore versatile control, adjustabilityand maneuverability of the towing or other winch operation. More in particular, the invention aims at providing a control system which, while permitting an automatic, variable torque operation according to the above-mentioned principle of the known machines, can also be caused to reduce or increase the datum torque of the winch motorunderload and under control by the oper,ator, thereby affording a much greater flexibility of control as obtained" in the control systems heretofore available. It is also intended bythis invention to achieve such torque adjustments; by means of simple electric switch or push button controls.

Another object of: my invention isto provide a variable voltage drive for towing machines, containing; variable torque control means of the.

manual or automatic type above-referredjto, with separate control means for paying out or heaving in under no-loadj'or light-load conditions andat a torque andf'speed' setting different fromthat of the towing operationproper in order to obtain optimum working conditions in either case of control:

It is also an object of the invention to devise a variable voltage system of winch control' in which theresistance of 'the generator. field circuit is automatically varied when heaving in and payingout, respectively, so as to reduce and'increasethetorque of the winchmotor to such an extent that the effect of the; winch friction-- eliminated.

These and other obilects will become apparent from the following description of the embodiments shown in the drawings, in which:

Figure 1 represents a circuit diagram of a complete winch control system in accordance with the invention, while Figs. 2, 3; 4 and 5 exemplify operating characteristics relating to the same system; and

Fig. 6 is a circuit diagram of another winch control system also. in accordance with my invention.

Referring to Fig. l, thewinchmotor isdenoted by WM. It is shafted to a gear-box GB containing a speed-reduction gear for driving the winch drum A brake Bis provided acting on the winch drum orits shaft. This brake is spring operated and electrically releasable. A- tens-iometric device T is associated with the winch drum for producing a control impulse on the winch motorwhen the rope tension exceeds a given limit; The motor WM is controlled by a generator G'which, in turn, is driven-by a constantspeed' motor M serving also to drive an exciter generator E for supplying direct current of constant voltage to'its output mains X and Y from which the generator and motor field windings are energized under control of a master switch MS and a set of push buttons PB and also under control by the above-mentioned tensiometer T and a set of limit switches LS which are'actuated' independence upon the length of rope paid out by the-drum WD.

More in detail, the winch motor WM has its armature l0|- acted uponby a separately excited field winding I02 which is shunted by a dis,- charge resistor "iii of high resistance and energized through leads 25' and 123 from the exciter mains X and Y through a resistor I05 controlled by arelay IM. The armature lfll is mounted on the input shaft I86 of the gearbox GB; Theroutput shaft Hi1; revolving: at reduced speed; is connectedwith the drum body I08 of the winch drum- WD containing the hawser- (towing cable or rope) N19; The magnet,

coil for releasing; the'spring-actuated brake B" is engaged; The; ratchet wheel H-l forms also the orbit gear of a planetary drive whose sun gear H4 is rigidly mounted on the drum shaft I01. The planetary gears H5 of the drive mesh with the orbit gear and the sun gear and are journaled on shafts which are mounted on the spider H3 of the tensiometer T. This spider is rotatable about the drum shaft I01 and is biased for counterclockwise rotation by a spring I I1. A control contact H8 is connected with the spider so as to be closed when the spider rotates in counterclockwise direction against the force of spring H1. Such rotation occurs only when the pull of rope I09 acting on the drum gear IH exceeds a safe limit corresponding to the setting of spring H1. The closure of the tensiorneter contact H8 passes a control impulse into the control system tending to change the torque of the winch motor WM towards reducing the cable pull, as will be apparent from the following.

-.The gear-box GB is provided with a traveling nut which causes a cam H9 to travel in the upward or downward direction depending upon the direction of rotation of the shafts I06 and I01. The limit switch LS has two contacts I20 and I 2I. Contact I20 is actuated when cam H9 travels in the upward direction beyond an adjusted limit position which corresponds to the desired length of rope paid out by the winch drum. Contact I2I is actuated when the travelingcam H9 moves downwardly beyond an adjusted position corresponding to the minimum rope length paid out by the drum. The operation of the two contacts has also the effect of changing the torque of the winch motor WM towards reestablishing the desired rope length,

between the adjusted maximum and minimum limits, as will also become apparent hereinafter.

The armature IOI of the winch motor WM is series connected with the armature I3I of the main generator G. A generator field winding I32 serving as an interpole and compensating winding is also arranged in the armature circuit. The generator G has a self-excited shunt winding I33 and a separately excited shunt winding I34 acting cumulatively on the armature I3I. The excitation of winding I33 is not changed during the operation of the control system, but can be adjusted by means of a rheostat I35. The excitation of the separately excited field winding I34 is controlled by a field circuit which contains a fixed resistor I36 and a resistor I31 of a manually adjustable potentiometer P whose slider is denoted by I38. This field circuit includes further two fixed resistors I39 and I40 and two series connected rheostats RB and RF. Numeral I4I denotes the resistor, and I-42 the slider of rheostat RB, while the resistor and slider of rheostat RF are designated by numerals I43 and I44, respectively. The two sliders I42 and I44 are mounted on a common shaft I45 which carries also the actuating arm I46 of a set of rheostat limit switches RS comprising a contact 141, which is opened when arm I46 reaches one end position, and a contact I48 to be opened by arm I46 when it reaches its other limit position. The armature I49 of an auxiliary rheostat motor RM is connected with the shaft I45 and contains two' field windings I50 and I5I. Winding I50 is wound for rotating the armature I 49 in the direction indicated by an arrow marked lower. When the rheostats are actuated in this direction, while their branch of the generator field circuit is rendered operative by the relay means to be described presently, the main generator G is caused to reduce its output voltage, thereby 4 lowering the torque of the winch motor W'M. When the rheostat motor RM is energized by its field winding I5I, its rotation is in the opposite direction, so that the rheostats RB and RF are caused to increase the field excitation of the main generator G, thus increasing the torque of the winch motor WM; 'Thearmature I3I of the main generator G is mounted on a shaft I60 which is driven by the armature ISI of the constant-speed motor M and carries also the armature I66 of the excited generator E. The drive motor M has a shunt field I62 whose excitation can be adjusted by means of a rheostat I63. A main switch 164 connects the motor M to a suitable current source denoted by I65. The exciter E has a self-excited shunt field I61 whose excitation is adjusted by a rheostat I68 which permits varying the direct-current 1 the brake B and the series resistor I05 in the motor field circuit has a control winding I1I which, when energized, closes the relay contacts I12 and I13. Two relays denoted by 2M and 3M are provided for controlling the connection of the above-mentioned potentiometer P and the rheostats RB and RF with the field winding I34 of the main generator G. The relay 2M has a winding I14 which, when energized, closes the contacts I15, I16 and I11 of the relay while opening a back contact I18. Similarly, relay 3M has a control coil I19 whose energization causes the contacts I80, I8I and I82 to close'and back contact I83 to open. The circuit of coil I14 extends over the back contact I83 of relay 3M, and the circuit of coil I19 extends over the back contact of relay 2M. In this manner, the two relays are electrically interlocked so that when relay 2M is energized and its back contact, opened, the relay 3M remains inoperative and vice versa. Consequently, only one of the two branches of the generator field circuit, that is, either the manually adjusted potentiometer P or the motor-driven rheostats RB and RF, can :be operative at a time. In order to obtain this result, the relays 2M and 3M may also be provided with a mechanical interlock, preferably in addition to the above-mentioned electric interlock.

The coil circuit of relay 2M extending through the back contact I83 of relay 3M is controlled by two relays by ICE. and ZCR. Relay iCR has a control coil I83 which, when energized, closes the contacts I84 and I 85. The coil I86 of relay 2CR actuates a normally open contact I81 and a normally closed contact I88, the latter serving to short-circuit the rheostat RB and the fixed field resistor I40 as long as coil I86 remains deenergized.

A timing relay denoted by TR has a main control coil I89 and a compensating coil I90 and limit value by means of a potentiometer I98 (1 .0. 8 m nt. n .9 ae s d r n operation of the control system. A short- The compensating V circuiting winding may be provided in relay in order to obtain an increased timing period. A time limit of three to five seconds, for in stance, is sufi'icient.

The set of push buttons PB includes a raise button I93 which when actuated serves to energize the auxiliary motor RM to run in the torque raising direction, and a lower button I94 for controlling the auxiliary motor to run in the torque lowering direction indicated by the arrow. A third push button I95 is provided for causing the winch motor 'WM to pay out at relatively high speed under noeload or light-load conditions. The push buttons are only operative when the master switch MS is in the manual position, but. are inefiective in the oil and automatic positions of switch MS. On the other hand, the contacts I20 and I2! of the payout limit sw tch are only connected to the exciter mains when the master switch is in the automatic position. The master switch is of the drum controller type; its contact segments are denoted by I96, and the appertaining contact fingers by I91. ihe control system includes also a number of interconnecting conductors which will be referred to in the follow ing description of the operation of the system.

In order to place the control system in operative condition, the main switch I64 is to be closed. This starts the drive motor M and causes the exciter E to supply its mains X and Y with constant voltage. The shunt field I02 of the winch motor WM is energized, but the field is weakened by the series resistor I05. The compensating winding I90 of the timing relay TR is energized and places the relay in receptive condition without actuating its contacts. Assuming that the master switch MS is in the oil position, the generator shunt field I34 remains deenergized because the relays 2M and 3M are deenergized. Since contact I12 of relay IM remains open, the spring of brake B is effective; that is, the brake is set and. the motor WM and drum WD remain stopped.

MS in manual position Wh n now the master switch is placed into manual position, the winch drive is under control of the push buttons PB. These buttons function in the following manner: Pressing the reelout button I95 will energize the relay 3M, if the ratchet pawl I I2 is disengaged and the contact II3 closed as shown in the drawings. The ene r. gizing circuit for relay 3M extends over the elements X, MS, I95, I22, II3, I23, I18, coil I19 of 3M, I24, I25, Y. Relay 3M closes its contacts I89, I8I and I82 while opening the interlocking back contact I83, thus renderin relay 2M ineifective. Due to the closure of contacts I8I and I82, the field circuit of the generator winding I34 is encrgized through the potentiometer P, the closed field circuit extending through the elements X, I26, I21, I8I, resistor I31 of P, I36, I34, I82, I24, I25, Y. As a result, the winch motor WM is energized by the generator G to run in the pay-out direction with a speed and torque characteristic as set by the reel-out potentiometer P. The closure of contact I89 energizes the coil I1I of the brake relay IM which, in turn, releases the brake B by closing contact I12 and places full voltage on the motor shunt field I92 by closing contact I13. These conditions prevail as long as the reel-out button I 95 is kept depressed. When the button is released, the motor WM is stopped and the brake B set. Hence the operation of button I95 permits arin 01 F99 des re .311921 of 1 1 the raise butto 9 is ressed. the

relay ICE is en r i ed th ou h ci cuit X, I9 8 I2 coil 83' of ICE N he som time, the rheostat motor RM is energized through S, I9 4, I 8, :I I I-48 fie1d .11 W of I49, Y. Relay IQR energizes the contactor 2M through X, I35, I83, coil I14 of 2M, I24, I25, Y. Contactor 2M energizes the generator field winding I34 through circuit Y, I25, I24, I11, I29, I34, 39, I88, resistor I43 of rheostat RF, I30, I16, I21, I26, X, and the rheostat RF driven by motor RM increases progressively the excitation of the generator and hence the torque of the winch motor WM. Contact I15 of relay 2M also energizes coil III of the brake relay IM, which releases the brake B by closing contact I12 and imposes full excitation on the field winding I92 of the winch motor by closing contact I13. As a result, the winch motor will pull in the rope under increasing torque until the raise button I93 is released.

- When the lower button I94 is actuated, the relay 20R becomes elfective through the circuit X, MS, I93, I94, I52, coil I86 of 2GB, Y. The rheosta-t motor RM is now connected with its flowering" field winding I50 in the circuit Y, I49, I50, I41, I52, I94, I93, MS, X and reduces the generator excitation. The contact I08 of 20R opens and inserts additional resistance I40 and MI into the generator field circuit for reducing the motor torque to a further extent. Relay 2M comes in through X, I81, I83, I14, I24, I25, Y, while relay SM is interlocked by the opening of contact I18 and stays deenergized. Hence the manually adjusted potentiometer P is now ineffective. The closure of contact I15 in relay 2M energizes the coil I'II of relay IM through Y, I24, I14, I15, I21, I26, Relay IM closes contact I12, thereby releasing the brake B, while contact I13 puts full voltage on the motor field. The winch motor WM is now again caused to pull in the rope, but with a decreasing torque due to the action of RB and R When during the actuation of either button 593 or I94, the motor standstill torque corresponding to the then prevailing excitation of the generator G is exceeded by the torque exerted on the motor shaft by the pull of the towing rope I09, the motor is forced to reverse its direction, and rope will be paid out. During the actuation of the push button I93 or I94, the rheostat motor RM will be in operation only as long as the arm I46 of the rheostat shaft I45 remains within the maximum and minimum limit positions. Upon passing beyond either position, the limit switch RS will automatically stop the further motion of the heostat motor.

In the above-described manner, the push button set PB permits a manual control of all steps required for the performance of a towing operation. The rope can be paid out or pulled in to any extent, and the torque of the motor can be elastically regulated so as to satisfy any occurring towing conditions.

MS in automatic position With the master switehMS set for automatic control, the winch drive is governed by the operation of the tensiometer I and the limit switch LS. As long as the traveling cam I19 of the limit switch LS is somewhere between the maxi,- mum and minimum contacts I20 and I2I, the winch motor remains deenergized and the brake B set.

When the tension the towing rope I09 increases to such an extent that the ten-siometer co act H8 doses. the contro coil I8 9 the timing relay TR is-energized through circuit Y, I89, I53, -I I8, l54,.contact I20 of LS, I55,-MS, X. The subsequent closure of the time relay contact I92 energizes relay. 2CR through Y, I86, I52, I 92, I54, 120, I55, MS, X, and the rheostat motor RM through circuit Y, I49, I50, I41, I52, I92, I54, I20, I55, MS, X. Relay 2 CR bring in 2M through X, I81, I83, coil I14 of 2M, I24, I25, Y. Relay 2M interlocks 3M at I18 and energizes the generator field by closing contacts I15 and I11. The generator field winding I34 is now energized through rheostats RB and RF by a circuit X, I26, I21, I16, I30, I43 ofRF, l4l of RB, I40,I39, I34, I29, I11, I24, I25, Y. That the field excitation of the main generator is supplied through 'both rheostats RF and RB in series connection so that the field is progressively weakened due to the operation of motor RM. Contact I15 of relay 2M energizes coil l1I of IM, and thereby releases the brake at I12 and puts full voltage on the motor at I13.

If permitted to turn'that far, the rheostat :motor RM will increase the weakening field resistance until the rheostat RB opens the field circuit by moving the slider I42 in'the lowering direction beyond the extent of the resistor I4I. Before this happens, however, the tensiometer contact II8 will have opened so that the timing :relay TR drops out a few seconds later, stopping the rheostat motor RM by opening its circuit at I92 and stopping also the winch motor WM by deenergizing relay 2CR due to the opening of its coil circuit at I92.

If the rope pull again increases until the tensiometer contact I I8 closes, the preceding operation is repeated. The torque of the winch motor WM may now have been lowered and the rope been paid out until the limit switch LS actuates its contact I20. This contact trips the timing relay TR by'opening the above-described energizing circuit of relay coil I89. The subsequent opening of contact I92 of TR opens the circuit of coil I35 of 2GB, and stops the rheostat motor RM which was running in the lowering" direction or had stopped due to the operation of the rheostat limit switch LS. The actuation of contact I23 of LS energizes relay ICR through circuit Y, coil I83 of ICR, I56, I26, I51, MS, X. Relay ICR seals itself in with contact I84 and energizes 2M by closing at I85 the circuit for coil I14 of 2M extending through X, I58, I85, I83, I15, I24, I25, Y. Contact I15 of 2M energizes coil I1I of IM which, in turn, releases the brake and puts full excitation on the field of the winch motor. The rheostat motor RM is now energized to run in the raising direction by the completion oi circuit Y, I49, II, I48, I9I, I56, I20, I51, MS, X, and the rheostat RF and RB are turned accordingly. This operation continues until either the minimum pay-out limit switch I2I opens, which stops the motors WM and RM and sets the brake B, orprovided themaximum pay-out contact I21] has closed againthe tensiometer T again causes the motor torque to be lowered. In

the latter case, relay ICR may remain energized by its sealed-in contact, but the opening of contact I5I of TR, due to the energization of coil I89 upon the closure of tensiometer contact II8, will interrupt the raise" circuit of therheostat motor.

As apparent from the foregoing, when the tension of the rope becomes too large while heaving in, the motor will reverse its direction of rotation in order to pay-out with the motor torque remaining in the original, heave-in direction. In

view of this change in rotating direction without directional change in torque, the considerable amount of frictional losses in which drives of this type must be taken into consideration. These losses may amount up to 30% or even more of the entire power consumption. The friction has to be overcome by the motor when heaving in, and by the hawser when paying out. If the motor torque remained constant during its change of running direction, the haw-ser pull would have to increase considerably, for instance to more than twice its value for a frictional loss of 30%, in order to make the motor reverse its direction for paying-out operation. Hence, to maintain the same pull, the motor torque has to be lowered considerably, for instance to about one-half of its heave-in value. The above-described use of a generator shunt field regulated by the rheostats RF and RB affords a control of the motor torque in the just-mentioned manner. For instance, when the tensiometer contact II 8 closes, both rheostats RF and RB are inserted in the field circuit of generator winding I34. This cuts the motor torque back to the required pay-out value so that the effect of the winch friction ispractically eliminated.

The diagrams of Figs. 2 through 5 serve to further elucidate these operating conditions byway of example, referring to a winch drive designed in accordance with the circuit diagram of Fig. 1.

In Fig. 2, the torque condition-s of a winch motor (WM in Fig. l) are represented by curve a in dependence upon the percentile excitation of the separately excited generator shunt field (I34 in Fig. 1).

It will be seen from curve a that under the exemplified operating conditions, a reduction in the separate generator excitation byapproximately 34% of the normal value reduces the motor torque by about 40% of its normal value.

The diagram of Fig. 3 shows in curves b and c the relation of the motor torque to the drum torque in percentile values with reference to the .same conditions as assumed in the diagram of Fig. 1. Curve b represents the conditions prevailing when the winch motor heaves in while overcoming also the winch friction, this friction being assumed as a constant friction torque of 20% of the full load motor torque. Curve 0 represents the case of operation in which the rope pull overcomes the motor torque as well as the friction in the winch, thereby causing the drum to pay out. A reduction in th motor torque of about 40% is required to shift the characteristic from curve I) to curve 0 when reversing the motor operation from heaving in to paying out according to this diagram. This change in torque is obtained by the above-described control of the motor-driven rheostats RB and RF whose operating characteristics are represented in Fig. 4.

Referring to Fig. 4, the ordinate of the diagram represents the resistance values of the rheostats RB and RF in ohms while the abscissa represents the amount of travel of the rheostat sliders expressed in percent of the full available travel distance. Curve d relates'to rheostat RB, and curve e to rheostat RF. The diagram shown in Fig. 5 simplifies diagrammaticallythe results obtained with a system according to Fig. 1 under the conditions illustrated by the diagrams of Figs. 2, 3, and 4. The curves fl through f6 represent speed torque diagrams of the winch motor, the portion above the abscissa referring to the positive or heave-in directlon of rotation of the drum-and winch motor,

while the lower portion of the diagram relates to the ne tive or pay-out direction of rotation. The characteristic fl prevails at automatic or manual operation when the motor-driven rheostats are adjusted for maximum torque, and the characteristic ft. is effective when the rheostats are adjusted for minimum torque. Hence, during the progressive operation of the automatic rheostat adjustment, the effective characteristic shifts from curvefl towards it or vice versa, passing through the intermediat characteristics denoted by f2 through f5. When a chahge in direction Occurs, the motor torque isv varied auto-v matically, due to the action of the tensiometer contact M2, for instance, by 40% in. ac ordan e with the diagram of Fig, 3, this shirt being indicated by way of example in curve ce- The characteristicdenoted by curve h exemplifies the conditions obtaining during the operation of the manual reel-out button I95.

The embodiment shown in Fig. 6 difiers from the above-described system in providing an automatic control governed merely by a pay-out limit switch, i. e. without employing, a tensiometric control device. Furthermore, an additional pushbuttoncontrol is provided for affording a highspeed reel-in operation at the will of the operator. The system of Fig. 6 is also difierent as regards the operation and energization of the winch motor and brake during a towing operation. De spite these difierences, however, the system of Fig. 6 is, in manyessential details, similar to the one described in the foregoing. In order to facilitate a comparison, the reference characters WM, G, M and lit are applied to Fig. 6 in the same mannor as to Fig. 1. Likewise the reference characters GB, s, WD, RB, RF, Rs, RM, P and MS used in Fig. 6 denote machinery and apparatus similar to those designated by the same reference characters in Fig. 1. The last two digits of the reference numerals applied to Fig. 6 are identical with the corresponding digits of the numerals in Fig. 1 wherever functionally comparable elements are concerned. c

The interconnection and cooperative relation of the winch motor WM to the gear-box GB, the brake B and the hawser drum WD a well as the circuit. connections of the winch motor with the cam generator G and the connection of the latter with the drive motor M, likewise the inter-relationof rheostats RB and RF to the auxiliary motor RM, are identical with those in the preceding embodiment. The other details of the system according to Fig. 6 will be fully understood from the following description of its operation,

With ,the master switch MS in the off position, the closure of the main switch 254 starts the auxiliary motor M and causes the exciter E to put voltage on the exciter mains X and Y. in shunt field 292 of winch motor WM is energized from X and Y through resistors 295 and 204 which weaken the motor field. The generator field winding 234 remains deenergi'zed because its circuit is'open at contacts 216, 21! of relay 2M and at contacts 28!, 292 of relay 3M. The brake B is set because Contact 212 of relay [M is open. The winch motor remains at rest.

294-) serve {to control thetowing operation, and

10 buttons B2 (295, 295) serve to heave in or pay out any desired length of rope within the available limits.

Pressing the reel-out button 295, when the ratchet pawl 212 is disengaged and hence contact 2|3 closed, will energize relay 3M through the circuit X, MS, 295, M3, 213, coil 219 of SM, 224, 225, Y. Relay 3M, by closing contacts 28! and 282, supplies energizing current to the generator field winding 234 through Y, 225, 224, 282, 234, 236, resistance 231 of P, 28l, 221, 226, X, while RB and RF remain disconnected from field winding 234 because contacts 216 and 211 of 2M remain open, 2M being inoperative due to the opening of interlock contact 283. The field energization of generator G is now dependent on the setting of manually adjustable potentiometer P. Contact 289 of 3M energizes coil 21! of IM through Y, 226, 221, 280, 21l, 224, 225, Y. Relay IM closes 212 thereby releasing brake B, and also closes 213 thereby shorting resistor 295 so that the winch motor WM obtains full field voltage. The motor is energized to pay out rope until button 295 is released.

For reeling in with no (or little) towing load, button 295 is depressed. This energizes relay HR through X, MS, 295, coil I59 of HR, Y. Con tact I99 of HR opens, thereby placin resistor 294 into the motor field circuit for increased motor speed. Contact 299 of HR closes also and establishes a circuit X, MS, 290, 294, coil 239 of !CR, Y, and also a circuit from 294 through 249, 25l, 249, Y. As a result, the rheostat motor RM starts running in the raising direction, and relay ICR, by closing. its contact 29!, energizes relay 2M through circuit X, 29!, 283, coil 214 of 2M, 224, 225, Y. This has the effect of en- 'ergizing the generator field winding 234 through circuit Y, 225, 224, contact 211 of 2M, 229, 234, 239, 240, 24! and 242 of RB, 24-3 and 244 of RF,

. 230, contact 216 of 2M, 6, X. Due to the operation of motor RM, the generator G is energized with increasing voltage. This, together with the reduced field energization of the winch motor WM, causes the latter to reel in at high speed.

The operation of buttons 295 and 295 thus permits paying in and out at will preparatory to a towing operating or reeling the rope in after completion of a tow. The buttons 293 and 294 are provided for controlling the rope length during a towing operation, i. e., under load, button 293 serving to obtain increasing torque or pull and hence a reduced rope length, and button 294 to obtain a reducing torque and hence a yieldingly increasing rope length under load. The function of these buttons, more in detail, is as follows.

Pressing reel-out button 295, when pawl 2!! is disengaged and contact 2l3 closed, will energize relay 3M through circuit X, MS, 295, 2|3, 218, coil 219 of SM, 224, 225, Y. Relay 3M energizes the generator shunt field 234 through circuit Y, 225, 224, contact 282 of SM, 234, 235, 231 of P, 23l of 3M, 221, 225, X. The winch motor WM will pay out with a speed and torque characteristic as set by the manually adjusted potentiometer P. Contact 289 of 3M energizes coil 21! of relay lM through X, 226, 221, 289, 21I, 224,225, Y. Relay IM closes 212 and releases the brake B, and also closes 213 thereby placing fullvoltage on the motor shunt field 252 by short-circuiting resistor 205. If the button 295 is released, the motor WM will stop and the brake B again be set.

Pressing the raise, button 293 will" energize coil'289 of relay [OR by closing circuit X, MS, 293, 264, 289, Y. Relay ICR closes 2 91 and thereby energizes 2M through circuit X, 291, 282, coil 214 of'ZM, 224, 225, Y. Interlock contact 218 opens and maintains 3M inoperative. Contacts 216 and 211 of 2M close the circuit of generator field Winding 234 through Y, 225, 224, 211 of 2M, 229, 234, 239, 288, 243 of FR, 235, 216 of 2M, 221, 226, X. 215 of 2M closes the circuit of coil 2' of IM through Y, 225, 224, 211, 215, 221, 226, X. Belay IM puts full voltage on motor WM at 213 and releases the brake B at 212. The motor reclaims the rope until stopped by the release of button 293. During this operation, the rheostat motor RM is energized to run in the raising direction, through Y, 249,255, 248, 294, 293, MS, X. Hence, RF is turned to reduce itsresistance and to increase the generator field excitation.

Pressing the lower, button 294 will energize relay 20R through X, MS, 293, 294, coil 285 of ZCR, Y. At the same time, rheostatmotor RM is energized to run in the lowering direction, throughX, MS, 29-3, 29 i, 252, 241, 255, 259, Y, so that the generator excitation decreases. Relay 2CR closes contact 284 and thereby enei gizes 2M through X, 25 3, 283, coil 21 of 2M, 224, 225, Y. 7 Relay 3M is locked by the opening of contact'218 of 2M. Contact 215 of 2M energizes coil 2' of IM which, at 212, releases the brake B and puts full voltage on the field winding 262 of the winch motor WM by shortening resistor 205 at 213. Contacts 216 and 211 of 2M close the energizing circuit of the generator shunt field winding 234 through Y, 225, 224, 211 of 2M, 229,234,239, 283, resistor 2 33 of RF, 23K], contact 216 of 2M, 221, 226, X. Motor WM will again reclaim the ropebut with decreasing torque due to the progressing reduction in generator field excitation caused by RF.

When" holding either button 293 or 294 depressed to obtain the operation described in the foregoing, the motor WM will heave in only as long as its standstill. torque, corresponding to the respective excitation of the generator, is not exceeded. Upon occurrence of an excessive pull,"

the motor is forcedto reverse its direction and to pay out as much rope as is needed to reduce the pull. Furthermore, when during the abovedescribed operation, controlled byeither button 253 or 234, the rheostat RF reaches either end position, the respective contact 241 or 253 will be opened by arm 266 so that the circuit of mice tor RM is interrupted. Upon such interruption, the further operation of motor WM occurs. without change in the generator excitation and hence at a constant torque. When paying out rope and reaching the maximum rope lengthier which the limit switch LS is set, the traveling cam 219 will close contact 22!] thereby energizing relay IFR through X, 225, 269, 224, 225, Y. Relay IFR closes 210 and thus shorts RF so that the resistance in the circuit of the generator field winding 234 is reduced to its minimumas determined by resistor 239. Hence, the torque of WM is immediately increased to a maximum. Conversely, if the rope length reaches the minimum for which L8 is set, the traveling nut "219' 12 MS in position #2 When MS is set in position #2, the B2 buttons 295 and 295' are disconnected so that relays HR and 3M cannot be energized. The winch is now under control only by the buttons BI and the limit switch LS. This position of the master switch is provided in order to prevent an inade vertent operation of the reel-out and high-speed reel-in buttons 295 and 295' after towing load has been placed on the rope. The length of rope is then controlled by the operation of the limit switch LS in accordance with the torque setting determined by the adjustment of the rheostat RF. This setting can be varied at will during the towing operation, i. e. under load, by operating the BI buttons as described in the foregoing. .During this towing operation, relay SM is permanently energized through circuit X, MS, 259, 283, coil 214 of 2M, 224, 225, Y, so that the ,circuit of the generator field winding 234 is closed at 216 and 211, placing, RB and RF in operation, while the closure of contact 215 causes relay I M to place full voltage on the field winding 202 of the winch motor WM by shorting field resistor 205. At the same time, the brake B is released by closure of 212 and stays released during the entire towing operation, 1. e. as long as MS is in position #2, so that the load is now taken up by the countertorque developed by the winch motor. Since, as demonstrated by the above-described embodiment, various modifications of my invention are possible without departure from its essence, I wish this specification to be understood as illustrative and not in a limiting sense.

Iclaim as my invention:

1. A variable voltage winch control system comprising, in combination, a winch drum, 3. winch motor in mutually effective driving connection with said drum, a generator for providing energization for said winch motor and having a field winding for controlling said energize.- tion, two sets of resistance means for controlling theexcitation of said field winding, selectively operable contactor means for connecting said field winding with said sets respectively, an auxiliary motor arranged in driving connection with one of said sets for varying the resistance value of said set in order to vary the torque of said motor accordingly, operator-controlled contact means for controlling said auxiliary motor to run in either direction for increasing and lowering said torque respectively, additional operator-controlled contact means for controlling said contactor means so as to connect said other set of resistance means with said field winding in order to cause said which motor to run said drum in pay-out direction in accordance with the setting ofs'aid other resistance means.

2; A variable voltage control system for a towing winch comprising, in combination, a winch drum and a rope thereon, a winch motor in mutually efiective driving connection with said drum, said'motor having a separately excited field winding, a generator having an armature connected with said winch motor and a field winding for controlling the voltage of said motor, rheostat means connected with said generator field winding for controllingits excitation, an auxiliary motor disposed in driving connection with said rheostat means for varying, their resistance adjustment in order to cause said generator to vary the torque of said winch motor, means for controlling said auxiliary motor to run in either direction for lowerin and raisins the torque of said winch arr-save 13 motor respectively, and separate control means under control by the operator and connected with said motor field winding as well as with said auxiliary motor for reducing the motor field ex citation while causing said auxiliary motor to ru-n'in torque raising direction when said separate control means are actuated in order to re claim said rope at high speed.

3. A variable voltage control system for a towing winch comprising, in combination, a winch drum for accommodating a towing rope, a'winch motor in mutually effective driving connection with said drum, a generator having an arma ture connected with said winch motor and afield winding for controlling the voltage of said motor,

device controlled by said drum and connected with said auxiliary motor for controlling it in dependence upon the tension in said rope.

4. A variable voltage control system for a towing winch comprising, in combination, a winch drum and a rope thereon a winch motor in mutually effective driving connection with said drum, a generator having an armature connected with said winch motor and a field winding for controlling the voltage of said motor, rheostat means connected with said field winding for controlling its excitation, an auxiliary motor disposed in drivin connection with said rheostat means for varying their resistance adjustment in order to cause said generator to vary the torque of said winch motor, manual contact means for controlling said auxiliary motor to run in either direction for lowering and raising the torque of said winch motor respectively, a tensiometric device controlled by said drum and having a contact actuated in response to the occurrence of a given maximum tension in said rope, a timing relay connected with said contact, said relay being connected with said auxiliary motor to control it so as to run in the torque lowering direction upon actuation of said contact.

5. A variable voltage winch drive comprising, in combination, a winch drum, a winch motor in mutually effective driving connection with said drum, a generator having an armature connected with said Winch motor and a field winding for controlling the voltage of said motor, resistance means connected with aid field winding for controlling its excitation, operator-controlled means for controlling said resistance means in order to adjust the torque condition of said motor, contact means connected with said resistance means for changing said excitation by an amount corresponding substantially to the frictional loss of the winch drive, and control means connected with said contact means for causing it to increase the resistance value of said resistance means for lowering the torque of said motor when said drum is caused to pay out and to decrease said resistance value for increasing said torque when heaving in, thereby eliminating substantially the dis- -turbingefiect oisaid frictional loss on the operationof the drive.

6.. A variable voltage control system for atowing winch, comprising a winch motor, a generator having an armature connected with said motor and afield winding for controlling the voltage generated by said armature, rheostat means con-' nected with said field winding for controlling its excitation, operator-actuable control means for setting said rheostat means in order to thereby adjust said generator for selected towing conditions of said motor, and operator-actuable contact means connected with said field winding and neost'at means for adjusting said generator for high speed operation of said motor independent of the setting of said rheostat means selected by said control means.

*2. A variablevoltage control system for a towin g winch, comprising a winch motor, a generator having an armature connected with said motor and field winding for controlling the voltage of said armature, rheostat means connected with said field winding for controlling its excitation, operator-actuable control means for setting said rheostat means in order to thereby adjust said generator for selected torque conditions of the towing operation of said motor, operation adjustable second rheostat means disposed for selecting a desired reeling out speed of said motor, operator actuable control means for energizing said field windin through said second rheostat means in order to cause said motor to run in the paying out direction in accordance with the selected setting of said second rheostat means, and interlock means associated with said first and second control means and said first and second rheostat means so that only one of said rheostat means is operative at a time.

3. A variable voltage control system for a towing winch, comprising a winch motor for controlling the paying out of rope, a generator disposed for energizing said motor and having a field winding, rheostat means connected with said field winding for controlling its excitation, a reversible auxiliary motor for adjusting said rheostat means, contact means connected to said auxiliary motor for controlling it to run in either direction in order to raise and lower respectively the torque of said winch motor during the towing operation of the latter, and limit responsive control means also connected with said motor for causing it to run in the reverse direction relative to the direction selected by said contact means, when the length of paid out rope departs from a desired range whereby said length is automatically returned to within said range.

9. A variable voltage control system for a towing winch, comprising a winch motor, a generator disposed for energizing said motor and having a field winding, rheostat means connected with said field winding for controlling its excitation, a reversible auxiliary motor for adjusting said rheostat means, contact means connected to said auxiliary motor for controlling it to run in either direction in order to raise and lower respectively the torque of said winch motor during the operation of the latter, and limit switch means interposed between said auxiliary motor and said contact means so as to prevent operation of said auxiliary motor in one direction when said winch motor exceeds a desired limit of travel in said one direction.

10. A variable voltage control system for a towing winch, comprising a winch drum for accommodating a towing rope, a winch motor in mutual driving connection with said drum, a generator'disposed for energizing said motor and having a field winding, rheostat means connected with said field winding for controlling its excitation, a reversible auxiliary motor for adjusting said rheostat means, contact means connected to said auxiliary motor for controlling it to run in either direction in order to raise and lower respectively the torque of said winch motor during the operation of the latter, and limit control means connected-with said rheostat means for automatically varying said excitation when the condition of the rope departs from given safe limits, whereby said torque is changed in the direction necessary to restore said rope condition to within said limits.

11. A variable voltage control system for a towing winch, comprising a winch drum for accommodating a towing rope, a winch motor in mutual driving connection with said drum, a generator disposed for energizing said motor and having a field winding, rheostat means connected with said field winding for controlling its excitation, a'reversible auxiliary motor for adjusting said rheostat means, contact means connected to said auxiliary motor for controlling it to run in either direction in order to raise and lower respectively the torque of said winch motor during the operation of the latter, and limit control means having relay means connected with said rheostat means and limit switch means for controlling said relay means in order to vary said excitation when the conditioner the rope departs from-given safe limits whereby said torque is changed in the direction necessary to restore said condition to within said limits.

KURT MAHNKE. 

